Turbine-driven dental handpieces are typically constructed so that they may be disconnected from their supply hoses when removal or replacement is desired. The connection is usually a threaded one with the operator either tightening or loosening a threaded coupling sleeve that brings the ported end face of a connector into or out of contact with a sealing gasket that surrounds a plurality of fluid supply tubes in the mating part. Such a gasket is depicted, for example, in co-owned U.S. Pat. No. 4,330,279 (FIG. 9).
While such an arrangement works well where handpieces are only infrequently attached and detached from their supply hoses, it is less desirable where frequent interchanging of handpieces is necessary. It is currently recommended that dentists use sterilized handpieces for each patient, thereby necessitating the interchange of handpieces for each new patient. Under such circumstances, the threading and unthreading of handpieces from their supply lines is not only time consuming but increases wear rate and the possibilities of leakage. Undertightening might obviously result in fluid leakage, and over-tightening may result in excessive deformations that may also result in leakage as well as increased wear and possible damage. Also, since modern handpieces are commonly equipped with means for illuminating an operative site, leakage might result in expensive damage to the electrical/optical components and potential injury or at least discomfort to the operator and patient.
Accordingly, an important aspect of this invention lies in providing a coupling that allows a handpiece to be quickly and easily connected or disconnected, with only a fractional turn of such a handpiece in relation to its hose coupling assembly, and at the same time insures the-application of a reproducible seal with a sealing force of predetermined magnitude whenever such parts are joined together. Since the applied sealing force is not in the control of the dentist or other operator, dangers of over-tightening or under-tightening are eliminated and with them the problems of leakage they might cause. Since over-tightening cannot occur, the distortions, deformations, possible damage, and increased wear caused by such over-tightening are avoided.
One aspect of this invention lies in the recognition that a bayonet-type lock might be ideally suited for a quick connect/disconnect coupling if the problems inherent in such a coupling were overcome primarily by springloading a connector body that makes sealing contact with the sealing gasket of a handpiece. By spring-loading the connector body, the reverse axial travel or backing-off inherent in bayonet lock operation when coupling or latching is fully achieved are nullified. The result is a coupling that permits rapid attachment and detachment without the disadvantages that might be expected from a bayonet lock arrangement.
Briefly, the coupling of this invention includes a hose connector assembly having a cylindrical first sleeve adapted to be joined at one end to a hose containing a drive air conduit, a secondary air conduit, and a water conduit. Within the first sleeve is a cylindrical connector body that is slidably mounted for axial movement between extended and retracted positions. The body has a smooth, hard distal end face and axially-extending passages through the body for communication with the conduits. Spring means in the first sleeve urges the body in a distal direction into its extended position, the spring means preferably taking the form of a helical compression spring of flat wire.
The coupling also includes a dental handpiece having a handle with a proximal end providing a cylindrical second sleeve dimensioned for rotatable telescoping engagement with the first sleeve. One of the two sleeves is provided with a plurality of J-shaped bayonet slots and the other with a plurality of lugs receivable in the slots for releasably coupling the sleeves in telescoped condition. The handpiece includes a plurality of tubes that project from its proximal end and are receivable in the passages of the connector body. Sealing means in the form of a resilient gasket is mounted within the second sleeve and surrounds the tubes for sealingly engaging the end face of the connector body when the sleeves are coupled together. The gasket surrounds the tubes along a portion of their length and integral frusto-conical sealing ring portions extend around each of the tubes for sealing engagement with the end face of the connector body. In addition, a rigid support ring backs and surrounds the gasket to control deformation of the gasket material and insure sealing effectiveness.
When the parts are coupled together, engagement between the gasket and the end face of the connector body cause displacement of the body into a partially retracted position. Such displacement is resisted by the force of the compression spring with the magnitude of such resistance being controllable during manufacture to insure effective sealing action.
Other advantages, features, and objects will appear from the specification and drawings.